As well-known in the art, image security system or monitoring system technologies for personal security using CCTV (Closed Circuit Television) cameras that are conventional analog cameras or network cameras have been developed. One of recent issues in the market is that the existing analog cameras are being changed to the network cameras, both of which coexist at present. Therefore, due to the appearance of the network cameras, users can connect to the network cameras to access or monitor image data collected by the network cameras under the environment where they are connected to a network anytime and anywhere. The appearance of the network cameras provides the above-stated convenience, but induces the security problem as well, thus causing the problem of an invasion of personal privacy. Thus, in order to solve this security problem, user authentication is required and image data needs to be encrypted upon transmission thereof. Further, to guard personal privacy against photo shooting that is unintentionally done in many image data, a privacy masking technique is often used.
In case of using the conventional analog camera, an image is taken by the analog camera, and digitalized and compressed by a DVR (Digital Video Recorder), which is an image storage device and connected to the analog camera via a coaxial cable or the like. Meanwhile, in case of using the network camera, the digitalization and compression functions are performed by the network camera itself. Also, the network camera is connected to an NVR (Network Video Recorder), which is an image storage device, via a wired/wireless network line such that the monitoring and management services can be conducted. In addition, as the performance of the network camera is improved, an image is also encoded and encrypted by the network camera for safe transmission thereof to the NVR or a video server. Therefore, a user who wants to monitor image data can monitor the desired image data by decrypting and decoding the safely encrypted image data.
However, this addition of the encryption function for security requires a method for safely storing and managing the image data and also requires differentiated image data that can be accessed depending on the user's authority. Thus, the user's personal security can be ensured more safely only when such security policy is conducted by a security management server that stores and manages the image data.